The cationic ruthenium−alkylidene complex [(PCy3)2(CO)(Cl)RuCHCHC(CH3)2]+BF4 - (1) was found to catalyze both hydrovinylation and [2+2] cycloaddition reactions of alkynes and alkenes. The reaction of R‘C⋮CR‘ ‘ (R‘ = H, Ph, n-Pr; R‘ ‘ = Ph, n-Pr, p-Tol, SiEt3, CH2CH2OH) with ethylene in the presence of 1 (3 mol %) produced the hydrovinylation products 2 and 3. The analogous reaction of dimethyl acetylenedicarboxylate (R‘ = R‘ ‘ = CO2Me) with ethylene and norbornene resulted in the formation of the [2+2] cycloaddition products 4. Based on the experimental evidence, a plausible mechanism of the hydrovinylation reaction has been proposed via a sequential insertion of alkyne and ethylene to the hydride complex 7.

Using an exchange reaction involving one PCy 3 ligand in HRu(CO)Cl(PCy 3 ) 2 (1) for one IMes, a ruthenium-hydride complex HRu(CO)Cl(PCy 3 )(IMes) (2) has been prepared. Complex 2 is an active catalyst in the hydrogenation of alkenes. A TON of 24 000 h -1 has been obtained at 100 °C under 4 atm of hydrogen. Addition of HBF 4 ‚OEt 2 as cocatalyst enhanced the catalytic activity.

A well-defined cationic Ru-H complex catalyzes the dehydrative C-H alkylation reaction of phenols with alcohols to form ortho-substituted phenol products. Benzofuran derivatives are efficiently synthesized from the dehydrative C-H alkenylation and annulation reaction of phenols with 1,2-diols. The catalytic C-H coupling method employs cheaply available phenols and alcohols, exhibits a broad substrate scope, tolerates carbonyl and amine functional groups, and liberates water as the only byproduct.

Alkenes and alcohols are among the most abundant and commonly used organic feedstock in industrial processes. We report a selective catalytic alkylation reaction of alkenes with alcohols that forms a carbon-carbon bond between vinyl carbon-hydrogen (C-H) and carbon-hydroxy centers with the concomitant loss of water. The cationic ruthenium complex [(C(6)H(6))(PCy(3))(CO)RuH](+)BF(4)(-) (Cy, cyclohexyl) catalyzes the alkylation in solution within 2 to 8 hours at temperatures ranging from 75° to 110°C and tolerates a broad range of substrate functionality, including amines and carbonyls. Preliminary mechanistic studies are inconsistent with Friedel-Crafts-type electrophilic activation of the alcohols, suggesting instead a vinyl C-H activation pathway with opposite electronic polarization.

The ruthenium hydride complexes C 5 Me 5 Ru(L)H 3 (L ) PPh 3 (1a), PCy 3 (1b), PMe 3 (1c)) were found to catalyze the dimerization reaction of terminal alkynes RCtCH (R ) Ph, t-Bu, SiMe 3 , CH 2 Ph, C 4 H 9 ) to produce cis-and trans-1,4-disubstituted enynes RCHdCHCtCR and 1,3-disubstituted enynes CH 2 dC(R)CtCR. The selective product formation was effected by modulating both the catalyst environment and the alkyne substrates. A rare form of dimer, cumulene PhCH 2 CHdCdCdCHCH 2 Ph (5d), was cleanly obtained from the dimerization of HCtCCH 2 Ph with 1b. A mechanistic interpretation is presented on the basis of the product distribution.

The cationic ruthenium-hydride complexes, [(PCy 3 ) 2 (CO)(CH 3 CN) 2 RuH] + BF 4 − and formed in situ from Ru 3 (CO) 12 /HBF 4 ·OEt 2 , were found to be highly effective catalysts for the C-H bond activation reaction of arylamines and terminal alkynes. The regioselective catalytic synthesis of substituted quinoline and quinoxaline derivatives was achieved from the ortho-C-H bond activation reaction of arylamines and terminal alkynes by using the catalyst Ru 3 (CO) 12 /HBF 4 ·OEt 2 . The normal isotope effect (k CH /k CD = 2.5) was observed for the reaction of C 6 H 5 NH 2 and C 6 D 5 NH 2 with propyne. A highly negative Hammett value (ρ = −4.4) was obtained from the correlation of the relative rates from a series of meta-substituted anilines m-X-C 6 H 4 NH 2 with σ p in the presence of Ru 3 (CO) 12 /HBF 4 ·OEt 2 (3 mol% Ru; 1:3 molar ratio). The deuterium labeling studies from the reactions of both indoline and acyclic arylamines with DC≡CPh showed that the alkyne C-H bond activation step is reversible. The crossover experiment from the reaction of 1-(2-amino-1-phenyl) pyrrol with DC≡CPh and HC≡CC 6 H 4 -p-OMe led to the preferential deuterium incorporation to the phenyl-substituted quinoline product. A mechanism involving rate-determining ortho-C-H bond activation and an intramolecular C-N bond formation steps via an unsaturated cationic rutheniumacetylide complex has been proposed.

The cationic ruthenium-hydride complex [(PCy3)2(CO)(CH3CN)2RuH]+BF4- (1) was found to be an effective catalyst for the regioselective coupling reaction of benzocyclic amines and terminal alkynes to form the tricyclic quinoline derivatives. The scope of the reaction was explored by using the catalytic system Ru3(CO)12/NH4PF6. The catalytically active cationic ruthenium-acetylide complex [(PCy3)2(CO)(CH3CN)2RuCCPh]+BF4- was isolated from the reaction of 1 with phenylacetylene.

[reaction: see text]. The cationic ruthenium complex [(PCy3)2(CO)(Cl)Ru=CHCH=C(CH3)2]+BF4- was found to be an effective catalyst for the coupling reaction of aniline and ethylene to form a approximately 1:1 ratio of N-ethylaniline and 2-methylquinoline products. The analogous reaction with 1,3-dienes resulted in the preferential formation of Markovnikov addition products. The normal isotope effect of k(NH)/k(ND) = 2.2 (aniline and aniline-d7 at 80 degrees C) and the Hammett rho = -0.43 (correlation of para-substituted p-X-C6H4NH2) suggest an N-H bond activation rate-limiting step for the catalytic reaction.